Plant Security Countermeasures

The essay is about veganism and plant eating, but I found the descriptions of plant security countermeasures interesting:

Plants can’t run away from a threat but they can stand their ground. “They are very good at avoiding getting eaten,” said Linda Walling of the University of California, Riverside. “It’s an unusual situation where insects can overcome those defenses.” At the smallest nip to its leaves, specialized cells on the plant’s surface release chemicals to irritate the predator or sticky goo to entrap it. Genes in the plant’s DNA are activated to wage systemwide chemical warfare, the plant’s version of an immune response. We need terpenes, alkaloids, phenolics—let’s move.

“I’m amazed at how fast some of these things happen,” said Consuelo M. De Moraes of Pennsylvania State University. Dr. De Moraes and her colleagues did labeling experiments to clock a plant’s systemic response time and found that, in less than 20 minutes from the moment the caterpillar had begun feeding on its leaves, the plant had plucked carbon from the air and forged defensive compounds from scratch.

Just because we humans can’t hear them doesn’t mean plants don’t howl. Some of the compounds that plants generate in response to insect mastication—their feedback, you might say—are volatile chemicals that serve as cries for help. Such airborne alarm calls have been shown to attract both large predatory insects like dragon flies, which delight in caterpillar meat, and tiny parasitic insects, which can infect a caterpillar and destroy it from within.

Enemies of the plant’s enemies are not the only ones to tune into the emergency broadcast. “Some of these cues, some of these volatiles that are released when a focal plant is damaged,” said Richard Karban of the University of California, Davis, “cause other plants of the same species, or even of another species, to likewise become more resistant to herbivores.”

There’s more in the essay.

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Posted on December 23, 2009 at 7:50 AM • 22 Comments

Comments

Clive Robinson • December 23, 2009 9:31 AM

” …some of these volatiles that are released when a focal plant is damaged”

Are also usefull to humans. In India they store grain and other foodstuffs with the leaves of certain plants as these act as chemical “keep aways” to a variety of creatures including rodents.

Another “volatil” group usefull to man are the opiates. The actual harvesting process (make a small cut in the seed head) apparently increases opiate production.

Oh and some “organic” gardeners know that the likes of chives can keep the likes of carrort fly off of other crops just by being planted next to them.

BF Skinner • December 23, 2009 10:01 AM

@Clive “some of these volatiles that are released when a focal plant is damaged”

Include peppers, Central American indians used / use dried chili peppers to drive insects away from food (better than knocking weavils out of ships biscuit eh?)

Extrapolating back to technical/made world; what are we talking about here?

Black Ice?

Auto anti-theft devices that attack the would-be thief? If we combine the self harvesting biodesiel DARPA design with the pitcher plant model todays would-be theif becomes tomorrows drive to work.

-IcanHasVeggieBruger • December 23, 2009 10:11 AM

As long as they aren’t self-aware, I eats them. Even then… yeah I’d still eats them, I love “antz on a log” 🙂

Nicko • December 23, 2009 10:27 AM

Those evil vegans! Eating poor, innocent, immobile plants, deaf to their howls. At least with us carnivores we chase animals that have a sporting chance to flee and we have to listen to their last, desperate gasps as they go down!

Tom • December 23, 2009 10:33 AM

Organic gardeners do companion planting all the time. Plant Marigolds/Nasturiums next to certain plants to reduce the incident of certain insects.

When you pick japanese beetles, put them in a bucket of soapy water and leave it out. The dead beetles will ward off others flying in.

BF Skinner • December 23, 2009 11:32 AM

@Tim B “how come the aphids are killing my shrubs”

Sounds like a failure in access control.
Do you have formal written policies on shrub access?
Did you write down your password?
Are your shrubs configured
– to lock out after n bad access attempts.
– use >=2 factor authentication
– age passwords and force change out after n days
– permit the least possible priviledge

mcb • December 23, 2009 12:42 PM

@ Tom

“When you pick japanese beetles, put them in a bucket of soapy water and leave it out. The dead beetles will ward off others flying in.”

If that doesn’t work you can impale them alive on toothpicks around the perimeter as a warning to all! Leaving just the heads on teeny weeny little pikes gives better results but it’s much more work.

jgreco • December 23, 2009 3:03 PM

@foo

Yeah, I always thought of that as the equivalent of changing the locks on your doors every month. Eventually you’re just going to get sick of spending money for a new lock every month and get a cheaper one. Instead of increasing security, security is decreased.

Ctrl-Alt-Del • December 23, 2009 3:23 PM

@ Nicko:
“At least with us carnivores we chase animals that have a sporting chance to flee and we have to listen to their last, desperate gasps as they go down!”

Hmm, I’m not a vegetarian but the last time I ate meat caught and killed in my presence (at least the sort that you have to chase down and which gasps audibly as it dies) was about 30 years ago – a feral goat. It’s good to hear that you still go out and catch your own instead of buying it from the meat section.

@ B F Skinner:

“a failure in access control”

No, it’s an education issue. The shrubs have to learn what they can do to avoid attracting the attention of the bugs.

Al Fidd • December 23, 2009 9:17 PM

@Ctrl-Alt-Del:

“No, it’s an education issue. The shrubs have to learn what they can do to avoid attracting the attention of the bugs.”

It’s the shrubs’ fault. They were asking for it! Can’t you see how provocatively dressed they are, with those wide green leaves arranged just so, to give you the barest glimpses of dainty little fruits just bursting with juice hanging on their gracefully slender branches, and their thick, round roots grasping the ground firmly in their woody embrace? And when the wind blows just so… well, you know.

Roger • December 24, 2009 1:14 AM

There is a fair (and growing) amount of evidence that most of the benefits of medicinal plants are hormesis effects. [1]

That is, the plant produces toxic chemicals to stop the nasty humans eating it, the humans evolved defence mechanisms to prevent poisoning by the plant, and consequently a moderate dose of the plant stimulates the protective mechanism. But a large enough dose is still, of course, harmful; which reflects both “the dose maketh the poison”, and the fact that the plants and herbivore arrive at some sort of evolutionary truce when the grazer’s best strategy is to nibble a little from each plant then move on and let them recover. Ripeness is another aspect of this: the plant tastes bad and in large doses may make you ill, if at a stage when eating it will harm its reproductive strategy. But wait a few days until the seeds are ready for dispersal, and it becomes tasty.

Another interesting corollary to this is that it is unlikely that many of our food plants have no defensive toxins at all. Thus overdoing any one plant is likely to have harmful effects no matter how much it is touted as a wonder food, and the best option is a varied diet.

  1. And some proponents of this theory are now also finding evidence that it is also true of many synthetic drugs. This answers a deep mystery that has been too little asked: how on earth can specific problems be solved, with minimal side effects, by throwing some random but highly specific chemical into the insanely complex mechanical / biochemical / electrical systems that are our bodies? It’s like saying you can fix a corrupted operating system by downloading a certain JPEG. It might happen, but the odds of it working are so astronomically low it is unlikely you ever find such a “magic bullet” without vastly superior knowledge of the body system than we in fact possess. However it makes sense if the function of the substance is simply to trigger a highly tuned repair mechanism which evolved over millions of years.

Clive Robinson • December 24, 2009 2:55 AM

@ Roger,

“Another interesting corollary to this is that it is unlikely that many of our food plants have no defensive toxins at all. Thus overdoing any one plant is likely to have harmful effects no matter how much it is touted as a wonder food”

Most of them do actually have quite nasty poisons potatos and rhubarb being two prime examples.

In both cases the poison is found in the green parts of the plant. Thus if you are old enough your mother would have told you to not cook or eat green potatos. It is something most under 40’s do not appear to know of which is rather worrying.

Another series of exampels are plants that “must be cooked” before they are edible the classic example are beans, most of which will give you an upset stomache if eaten under cooked. However red kidney beans (used in chilly con carne and other Mexican food) will kill you.

Likewise the “caster bean” has one of the most deadly toxins known which is ricin which was used to kill the disident Georgy Markoff. Swallowing just one raw bean will be leathal in the majority of people…

Then there are herbs and spices many are poisons but have medicinal properties in moderate amounts and taste nice in small amounts.

One such spice is “mace” which is the outer casing of the nutmeg. It is said to have similar effects to some recreational drugs.

One such herb is “wormwood” which gives the green colour to Absinth.

There are others such as “cleary sage” which is usually available as an essential oil.

Peter E Retep • December 26, 2009 5:02 PM

re: Clive

I teach my students that all plants one sees growing wild are toxic. Otherwise they would have bee eaten. Once the idea is grasped, the narrower envelope of edible lures to spread seeds, and of the specialized abilities of it eaters to withstand certain toxins, become evident and important.

Then the organic question comes up: would you rather have an insect specific growth disruptor, external and easily washed off, or eat the the brown spot that triggers hudreds or thousands of new toxins profuced inside the whole plant, which you also ingest?

In California, a few seasons back, in the effort to avoid spraying in a washable pesticide, and claim “safe yet organic”, a wonder celery was developed which was ‘resistant’ to insect pests. The main result was a recall, when the celery blistered the mouths and some hands, of customers.

Clive Robinson • December 26, 2009 8:00 PM

@ Peter E Retep,

“would you rather have an insect specific growth disruptor, external and easily washed off, or eat the the brown spot that triggers hudreds or thousands of new toxins profuced inside the whole plant, which you also ingest?”

Honest answer is it depends.

If the plant concerned had been in my ansesters food supply for many generations then I’d go for the brown spot.

If however the plant had not been part of my ancesters food supply then I’d treat it with caution any way (MSG and penuts being a couple of cases in point).

As for pesticides etc I’m not very happy about them or food adatives simply because the testing process is fairly easy to rig and has been in the past.

Also we have a bad track record on such things (think about hydrogenated vegtable oils, silicon oils used in food production, some orange colourings, oh and how about additives to chocolate supposedly ok for humans but will kill the family pet dog).

If however it was from a natural source (such as pyrethans) I would be a little less worried (However there are exceptions such as cyanide laden Koala food 😉

Then there is the issue of the “test group” we know that there are people who won’t be poisoned by arsnic or die if they eat death cap fungi. Some south american natives quite happily injest certain plant extracts that make them high but would kill the average European.

As a broad example what about the Japanese intolerance to alcohol it was about 50% of the population just after WWII geting drunk on a single glass of beer or wine.

In Europeans however the level of intolerance is about 1 in 10,000 (depending on who’s figures you belive).

Apparently we have bred it out of European genetic stock simply because your life expectancy less than 200 years ago was below breeding age if you had alcohol intolerance…

As for GM sorry I won’t touch it for a simple reason. Man’s oldest GM crop is wheat, and after several thousand years something like 1% of the population can be killed by eating various varieties of it…

Also I just don’t trust the likes of a certain well known US GM entity that has a history of very very underhanded tricks with supplying seed that requires certain fertilizers etc.

Also the “pro” arguments put forward apear to be based on unproven or false arguments such as birth rate predictions in Asia and Africa and land fertility in those areas.

Then of course there is the “kill switch” gene that has provoked a “hold the world to ransom” “domesday senario” from some of the “anti” campaing which goes something like,

“Imagine the money to be made if you could find a GM variety that would be (semi) ok to eat for adults but effected their unborn children subtaly by effecting say their development into adults. But this could be treated in the effected population by them having to take a life long medication, which the GM company only patents at the appropriate time…

Silly and far fetched yes impossible who knows 😉

As I said I’d rather take my chances with plant toxins my grandfather and earlier ate on a regular basis, the chances are I’ve inherited a degree of immunity 8)

Scary devil Monastery • January 4, 2010 1:25 PM

There’s a certain kind of african acacia tree whose natural defenses make it the be-all end-all of natural fortresses. The root system poisons the soil around the tree in a 30 feet radius, rendering the ground unfertile to anything but the hardiest of grasses, the plant is covered in spines, highly toxic to nearly any type of predator…and it hosts a vicious ant colony in hollowed-out nodules in it’s body which deters any would-be assailant.

Something to learn from.

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